U.S. patent application number 16/245715 was filed with the patent office on 2019-05-16 for deformation detection sensor, electronic device, and method for manufacturing detecting deformation detection sensor.
The applicant listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Masamichi Ando, Jun Endo, Takashi Kihara.
Application Number | 20190145838 16/245715 |
Document ID | / |
Family ID | 61072702 |
Filed Date | 2019-05-16 |
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United States Patent
Application |
20190145838 |
Kind Code |
A1 |
Kihara; Takashi ; et
al. |
May 16, 2019 |
DEFORMATION DETECTION SENSOR, ELECTRONIC DEVICE, AND METHOD FOR
MANUFACTURING DETECTING DEFORMATION DETECTION SENSOR
Abstract
A deformation detection sensor that includes a conductive
member, a plurality of thermoplastic resin layers, and a
piezoelectric film. At least one of the thermoplastic resin layers
has a main surface, and the conductive member is formed on the main
surface thereof. The plurality of thermoplastic resin layers are
laminated and integrally formed by hot pressing into a laminated
body. A transmission line is formed form a first portion of the
conductive member and the thermoplastic resin in the laminated
body. The piezoelectric film is attached to the laminated body to
form a piezoelectric element made of a second portion of the
conductive member, the thermoplastic resin in the laminated body,
and the piezoelectric film.
Inventors: |
Kihara; Takashi;
(Nagaokakyo-shi, JP) ; Endo; Jun; (Nagaokakyo-shi,
JP) ; Ando; Masamichi; (Nagaokakyo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Nagaokakyo-shi |
|
JP |
|
|
Family ID: |
61072702 |
Appl. No.: |
16/245715 |
Filed: |
January 11, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2017/025706 |
Jul 14, 2017 |
|
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|
16245715 |
|
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Current U.S.
Class: |
310/338 |
Current CPC
Class: |
G01L 1/162 20130101;
H01L 41/193 20130101; H01L 41/1132 20130101; G01L 1/16 20130101;
G01L 9/08 20130101; G01L 5/22 20130101 |
International
Class: |
G01L 1/16 20060101
G01L001/16; G01L 5/22 20060101 G01L005/22; H01L 41/113 20060101
H01L041/113; G01L 9/08 20060101 G01L009/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2016 |
JP |
2016-152500 |
Claims
1. A deformation detection sensor comprising: a thermoplastic resin
body which has a main surface; a conductive member on the main
surface of the resin body; and a piezoelectric film attached to the
thermoplastic resin body, wherein a first portion of the conductive
member and the thermoplastic resin body are arranged to form a
transmission line, and a second portion of the conductive member,
the thermoplastic resin body, and the piezoelectric film are
arranged to form a piezoelectric element.
2. The deformation detection sensor according to claim 1, wherein
the piezoelectric film and the transmission line are disposed so as
to overlap each other in a planar view, and a ground conductor is
positioned between the piezoelectric film and the transmission
line.
3. The deformation detection sensor according to claim 1, wherein
the piezoelectric element and the transmission line are disposed so
as to not overlap each other in a planar view.
4. The deformation detection sensor according to claim 3, wherein
the thermoplastic resin body between the piezoelectric element and
the transmission line is bent.
5. The deformation detection sensor according to claim 1, wherein
the transmission line and a signal line of the piezoelectric
element are made of a single conductive member.
6. The deformation detection sensor according to claim 1, wherein
the first portion of the conductive member includes a first signal
line and a second signal line, and a part of the thermoplastic
resin body is removed between the first signal line and the second
signal line.
7. The deformation detection sensor according to claim 6, wherein
the first portion of the conductive member and the second portion
of the conductive member are separate from each other.
8. The deformation detection sensor according to claim 1, wherein
the first portion of the conductive member and the second portion
of the conductive member are separate from each other.
9. The deformation detection sensor according to claim 1, wherein
thermoplastic resin body includes a resin base material selected
from a liquid crystal polymer resin, polyetheretherketone,
polyetherimide, polyphenylene sulfide, or polyimide.
10. An electronic device comprising: a casing; and the deformation
detection sensor according to claim 1 within the casing; and
wherein a main surface of the piezoelectric film is arranged
parallel to a side surface of the casing.
11. A method for manufacturing a deformation detection sensor, the
method comprising: preparing a plurality of thermoplastic resin
layers, at least one of which has a main surface on which a
conductive member is formed; laminating the plurality of
thermoplastic resin layers; after lamination, integrally forming
the plurality of thermoplastic resin layers by hot pressing to
obtain a laminated body configured so that a transmission line is
formed from a first portion of the conductive member and the
laminated body; and attaching a piezoelectric film to the laminated
body so that a piezoelectric element is formed from a second
portion of the conductive member, the laminated body, and the
piezoelectric film.
12. The method for manufacturing a deformation detection sensor
according to claim 11, wherein the piezoelectric film and the
transmission line are disposed so as to overlap each other in a
planar view, and a ground conductor is positioned between the
piezoelectric film and the transmission line.
13. The method for manufacturing a deformation detection sensor
according to claim 11, wherein the piezoelectric element and the
transmission line are disposed so as to not overlap each other in a
planar view.
14. The method for manufacturing a deformation detection sensor
according to claim 13, wherein the laminated body between the
piezoelectric element and the transmission line is bent.
15. The method for manufacturing a deformation detection sensor
according to claim 11, wherein the transmission line and a signal
line of the piezoelectric element are made of a single conductive
member.
16. The method for manufacturing a deformation detection sensor
according to claim 11, wherein the first portion of the conductive
member includes a first signal line and a second signal line, and a
part of the laminated body is removed between the first signal line
and the second signal line.
17. The method for manufacturing a deformation detection sensor
according to claim 16, wherein the first portion of the conductive
member and the second portion of the conductive member are separate
from each other.
18. The method for manufacturing a deformation detection sensor
according to claim 11, wherein the first portion of the conductive
member and the second portion of the conductive member are separate
from each other.
19. The method for manufacturing a deformation detection sensor
according to claim 11, wherein laminated body includes a resin base
material selected from a liquid crystal polymer resin,
polyetheretherketone, polyetherimide, polyphenylene sulfide, or
polyimide.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of International
application No. PCT/JP2017/025706, filed Jul. 14, 2017, which
claims priority to Japanese Patent Application No. 2016-152500,
filed Aug. 3, 2016, the entire contents of each of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a deformation detection
sensor that detects a deformation operation on an operation object,
an electronic device that includes the deformation detection
sensor, and a method for manufacturing the deformation detection
sensor.
BACKGROUND OF THE INVENTION
[0003] In recent years, a large number of electronic components
have been mounted in portable electronic devices such as
smartphones.
[0004] Patent Document 1 discloses a transmission line formed of a
thermoplastic resin having flexibility, as an example of an
electronic component. [0005] Patent Document 1: PCT International
Publication No. WO2011/018979
SUMMARY OF THE INVENTION
[0006] In recent years, downsizing of electronic components has
been demanded. On the other hand, the number of electronic
components to be mounted is increasing.
[0007] Accordingly, an object of the present invention is to
provide a deformation detection sensor that not only functions as a
transmission line, but also is capable of performing an additional
plurality of functions, an electronic device including the
deformation detection sensor, and a method for manufacturing the
deformation detection sensor.
[0008] The deformation detection sensor in accordance with an
aspect of the present invention includes a conductive member, a
plurality of thermoplastic resin layers, and a piezoelectric film.
At least one of the thermoplastic resin layers has a main surface,
and the conductive member is formed on the main surface thereof.
The plurality of thermoplastic resin layers are laminated and
integrally formed by hot pressing into a laminated body. a
transmission line is formed from a first portion of the conductive
member and the thermoplastic resin in the laminated body. The
piezoelectric film is attached to the laminated body to form a
piezoelectric element made of a second portion of the conductive
member, the thermoplastic resin in the laminated body, and the
piezoelectric film.
[0009] The transmission line and the deformation detection sensor
are thus simply integrated to one thermoplastic resin (an
insulating base material having flexibility, such as polyimide, PET
or liquid crystal polymer), whereby high heat is not applied to the
piezoelectric film constituting the deformation detection sensor
during manufacture. This is because the piezoelectric film is
attached to the laminated body after the laminated body is formed
by hot pressing, so that high heat is not applied to the
piezoelectric film.
[0010] According to the present invention, it is possible to
realize the deformation detection sensor that not only functions as
a transmission line, but also is capable of performing an
additional plurality of functions.
BRIEF EXPLANATION OF THE DRAWINGS
[0011] FIG. 1 is a plan view of an electronic device including a
deformation detection sensor.
[0012] FIG. 2(A) is a transparent perspective view from a rear
surface side of a casing, and FIG. 2(B) is a partially enlarged
view of the rear surface of the casing.
[0013] FIGS. 3(A), 3(B), 3(C) and 3(D) are exploded perspective
views of the deformation detection sensor.
[0014] FIG. 4 is a cross-sectional view of line A-A illustrated in
FIG. 3(C).
[0015] FIGS. 5(A), 5(B), 5(C) and 5(D) are views illustrating a
step of manufacturing the deformation detection sensor.
[0016] FIGS. 6(A), 6(B) and 6(C) are cross-sectional views
illustrating a structure of a modification of the deformation
detection sensor.
[0017] FIGS. 7(A) and 7(B) are views illustrating an example of an
arrangement aspect of the deformation detection sensor in the
casing.
[0018] FIG. 8 is a cross-sectional view when a bent portion is
provided in the deformation detection sensor.
[0019] FIG. 9 is a cross-sectional view when a piezoelectric sensor
and a transmission line are laminated.
[0020] FIG. 10 is a cross-sectional view illustrating an example in
which a conductive thin film member is connected to a second ground
conductor.
[0021] FIGS. 11(A), 11(B), 11(C) and 11(D) are exploded perspective
views of the deformation detection sensor.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 is a plan view of an electronic device 1 including a
deformation detection sensor 10. In FIG. 1, only major components
are illustrated, and other components are omitted.
[0023] The electronic device 1 is an information processing device
such as a smartphone. As illustrated in FIG. 1, the electronic
device 1 includes a casing 50. The casing 50 houses the deformation
detection sensor 10, a printed circuit board 171, a printed circuit
board 181, and a battery module 81.
[0024] For example, various components such as a controller, a
memory, and a camera module of the electronic device 1 are mounted
on the printed circuit board 171. For example, a component such as
an antenna is mounted on the printed circuit board 181. The printed
circuit board 171 and the printed circuit board 181 are connected
via the deformation detection sensor 10.
[0025] The deformation detection sensor 10 is in contact with the
inner surface of the casing 50 and detects a deformation operation
on the casing 50. FIG. 2(A) is a transparent perspective view from
a rear surface side of the casing, and FIG. 2(B) is a partially
enlarged view of the rear surface of the casing. As illustrated in
FIGS. 2(A) and 2(B), a volume operation unit 501 displayed as "+"
and a volume operation unit 502 displayed as "-" are arranged on
the rear surface of the casing 50. The volume operation unit 501
and the volume operation unit 502 are formed on the surface of the
casing 50 by printing or the like, but are not physical operators.
A user presses the position of the volume operation unit 501 or the
volume operation unit 502 in the casing 50 to perform a volume
change operation.
[0026] When the user presses the position of the volume operation
unit 501 or the volume operation unit 502 in the casing 50 in order
to perform the volume change operation, the bottom surface of the
casing 50 is distorted at the center of the pressing position
toward the inner surface side. The deformation detection sensor 10
is in contact with the casing 50, and thus the sensor is distorted
along with the distortion of the casing 50. The deformation
detection sensor 10 has a detection electrode at a position
corresponding to the position of the volume operation unit 501 or
the volume operation unit 502, detects distortion at the position
corresponding to the position of the volume operation unit 501 or
the volume operation unit 502, and receives the volume change
operation corresponding to the detected distortion.
[0027] FIGS. 3(A), 3(B), 3(C) and 3(D) are exploded perspective
views illustrating the structure of the deformation detection
sensor 10. FIG. 4 is a cross-sectional view of line A-A in FIG.
3(C).
[0028] In FIGS. 3(A), 3(B), 3(C) and 3(D), the deformation
detection sensor 10 includes a first ground conductor 101, a resin
base material 102, a resin base material 103, a second ground
conductor 104, a signal line conductor 105, a first detection
electrode 107, a second detection electrode 109, a piezoelectric
film 150, and a conductive thin film member 170. As illustrated in
FIGS. 11(A), 11(B), 11(C) and 11(D), a slit 1021 may be provided
between the first detection electrode 107 and the second detection
electrode 109 of the resin base material 102. The slit 1021 extends
from the outer side of the resin base material 102 toward the
center thereof. Further, a through hole or a groove may be provided
in place of the slit 1021. That is, the resin base material 102 may
have a portion thereof removed between the first detection
electrode 107 and the second detection electrode 109 (a first
conductive member and a second conductive member). A length of the
slit 1021 is not limited as long as the slit 1021 is at least
slightly located between the first detection electrode 107 and the
second detection electrode 109. The slit 1021 assists in preventing
deformation of the resin base material 102 from being transmitted
to the second detection electrode 109 when the first detection
electrode 107 is pressed. Similarly, the slit 1021 assists in
preventing deformation of the resin base material 102 from being
transmitted to the first detection electrode 107 when the second
detection electrode 109 is pressed. This prevents unintentional
reaction of the adjacent operation units.
[0029] In FIGS. 3(A), 3(B), 3(C) and 3(D), the resin base material
102 and the resin base material 103 are described as separate
configurations. However, as illustrated in FIG. 4, the resin base
material 102 and the resin base material 103 are preferably made of
the same kind of thermoplastic resin, and are integrated by hot
pressing.
[0030] The thermoplastic resin is a resin base material having
flexibility, and is made of, for example, a liquid crystal polymer
resin. It is to be noted that examples of thermoplastic resins
other than the liquid crystal polymer resin include
polyetheretherketone (PEEK), polyetherimide (PEI), polyphenylene
sulfide (PPS), polyimide (PI), and these resins may be used in
place of the liquid crystal polymer resin. It is to be noted that,
since the liquid crystal polymer is excellent in water resistance,
it is possible to realize a stable pressure sensitivity even under
a humid environment by laminating the liquid crystal polymer on
both sides of the piezoelectric film which is susceptible to
humidity like PLLA.
[0031] FIGS. 5(A), 5(B), 5(C) and 5(D) are views illustrating the
method for manufacturing the deformation detection sensor.
[0032] As illustrated in FIG. 5(A), a thermoplastic resin having a
main surface on which a conductive member is formed is first
prepared in order to manufacture the deformation detection sensor
10. At this time, in the conductive member formed on the upper
surface of the resin base material 102, the signal line conductor
105, the first detection electrode 107, the second detection
electrode 109, and other wiring lines are patterned. The signal
line conductor 105, the first detection electrode 107, and the
second detection electrode 109 are integrally formed by etching or
the like, so that an interval between the electrodes can be made
constant. The conductive member formed on the lower surface of the
resin base material 102 becomes the first ground conductor 101.
Then, as illustrated in FIG. 5(B), a plurality of thermoplastic
resins (in this example, the resin base material 102 and the resin
base material 103) are laminated and hot-pressed to obtain an
integrally formed laminated body.
[0033] In this manner, a triplate-type transmission line is made of
the first ground conductor 101 formed on the lower surface of the
resin base material 102, the signal line conductor 105 formed on
the upper surface of the resin base material 102, and the second
ground conductor 104 formed on the upper surface of the resin base
material 103. As illustrated in FIG. 1, the transmission line is
connected to the printed circuit board 171 and the printed circuit
board 181 to transmit a high frequency signal.
[0034] Thereafter, as illustrated in FIG. 5(C), in the laminated
body, the piezoelectric film 150 is attached to the upper surface
of the resin base material 102 using an adhesive or the like so as
to cover the first detection electrode 107 and the second detection
electrode 109.
[0035] For example, PVDF or a chiral polymer is used for the
piezoelectric film 150. In the case of using the chiral polymer,
more preferably, uniaxially stretched polylactic acid (PLA) is
used, and more specifically, L-type polylactic acid (PLLA) is used.
The uniaxial stretching direction of the polylactic acid is a
direction forming approximately 45.degree. with respect to the
longitudinal direction of the piezoelectric film 150. Approximately
45.degree. means 45.degree..+-.10.degree.. When the uniaxial
stretching direction is 45.+-.10.degree., the piezoelectric film
150 can exhibit good pressure sensitivity. Further, the uniaxial
stretching direction may be in a range greater than .+-.10.degree.
depending on the intended use.
[0036] The chiral polymer has a main chain in a helical structure,
and has piezoelectricity by uniaxial stretching to obtain molecule
orientation. The chiral polymer produces the piezoelectricity in a
molecule orientation processing by stretching or the like, and does
not need to be subjected to poling processing unlike other polymers
such as PVDF and piezoelectric ceramics. Particularly, since
polylactic acid has no pyroelectricity, even when the user presses
the casing 50 and the heat of the user's finger or the like is
transmitted, the amount of the detected electric charge remains
unchanged. Further, a piezoelectric constant of uniaxially
stretched PLLA belongs to a group of very high piezoelectric
constants among polymers. For example, PLLA can achieve a high
piezoelectric strain constant d.sub.14 of 10 to 20 pC/N if the
conditions such as a stretching condition, a heat treatment
condition, and formulation of additives, are right. Furthermore,
the piezoelectric constant of PLLA does not fluctuate over time and
is extremely stable.
[0037] It is to be noted that a stretch ratio of the piezoelectric
film is preferably about three to eight times. Performing heat
treatment after stretching encourages crystallization of extended
chain crystal of polylactic acid to improve the piezoelectric
constant. It is to be noted in the case of biaxial stretching, it
is possible to obtain a similar effect to that of uniaxial
stretching by making stretch ratios of the respective axes
different. For example, when a film is stretched eight times in a
direction as an X axis direction and is stretched two times in a Y
axis direction orthogonal to the X axis, it is possible to obtain
almost the same effect of the piezoelectric constant as the case
where a film is uniaxially stretched about four times in the X axis
direction. Since a simply uniaxially stretched piezoelectric film
is likely to split along a stretching axis direction, it is
possible to increase the strength to some extent by biaxially
stretching as described above.
[0038] Next, as illustrated in FIG. 5(D), the conductive thin film
member 170 is attached to the upper surface of the piezoelectric
film 150. The conductive thin film member 170 functions as a ground
conductor (a shield conductor). For example, a conductive nonwoven
fabric with an adhesive formed thereon or a resin-impregnated
copper foil with an adhesive formed thereon is used for the
conductive thin film member 170. The conductive thin film member
170 has lower rigidity than that of the first ground conductor 101
and the second ground conductor 104 so as not to hinder the
deformation of the piezoelectric film 150. As illustrated in FIG.
10, the conductive thin film member 170 may be connected to the
second ground conductor 104. However, the conductive thin film
member 170 is not an essential component.
[0039] The piezoelectric film 150 is attached to the laminated body
in the above-described manner so that a piezoelectric element is
made of the first detection electrode 107 and the second detection
electrode 109 formed on the upper surface of the resin base
material 102 and the piezoelectric film 150. The piezoelectric
element is connected to a not-illustrated controller of the
deformation detection sensor 10 (or the controller of the
electronic device 1) via wiring lines. The controller detects
electric charges generated in the first detection electrode 107 and
the second detection electrode 109 to detect distortion of the
position of the volume operation unit 501 or the volume operation
unit 502 in the casing 50, and receives the volume change operation
from the user.
[0040] The deformation detection sensor 10 has a structure in which
the piezoelectric film 150 is attached to the laminated body
integrally formed by hot pressing after the hot pressing.
Therefore, high heat is not applied to the piezoelectric film 150
at the time of manufacturing the deformation detection sensor
10.
[0041] As illustrated in FIGS. 3(B) and 4, the piezoelectric film
150 is disposed at a different position from the resin base
material 103 on the side of the transmission line, in a planar
view. That is, the piezoelectric film 150 and the transmission line
are disposed so as not to be overlapped in a planar view.
Therefore, even in the case where the piezoelectric film 150 and
the resin base material on the side where the piezoelectric film
150 is disposed are distorted when the user presses the casing 50,
the resin base material on the side of the transmission line does
not deform greatly, and the impedance of the transmission line does
not change significantly.
[0042] Next, FIGS. 6(A), 6(B) and 6(C) are cross-sectional views
illustrating a structure of the deformation detection sensor
according to a modification.
[0043] In the deformation detection sensor illustrated in FIG.
6(A), the resin base material 103 is also disposed on the side of
the piezoelectric element, and the cross-sectional shape thereof is
rectangular. Also, in this case, the deformation detection sensor
is manufactured by attaching the piezoelectric film 150 to the
laminated body integrally formed by hot pressing after the hot
pressing. Thus, it is possible to realize the deformation detection
sensor 10 including the function of the transmission line without
subjecting the piezoelectric film 150 to high heat. Further, the
piezoelectric film 150 and the transmission line are disposed so as
not to overlap each other in a planar view. Therefore, even in the
case where the piezoelectric film 150 and the resin base material
on the side where the piezoelectric film 150 is disposed are
distorted, the resin base material on the side of the transmission
line does not deform greatly, and the impedance of the transmission
line does not change significantly.
[0044] Further, as illustrated in FIG. 6(B), in the aspect in which
the resin base material 102 is not disposed on the side of the
piezoelectric element, similarly, the piezoelectric film 150 and
the transmission line are disposed so as not to overlap each other
in a planar view. Accordingly, in the case where the piezoelectric
film 150 and the resin base material on the side where the
piezoelectric film 150 is disposed are distorted when the user
presses the casing 50, the resin base material on the side of the
transmission line does not deform greatly, and the impedance of the
transmission line does not change significantly.
[0045] The deformation detection sensor 10 in FIG. 6(C) is an
example in which the signal line conductor 105, the first detection
electrode 107, and the second detection electrode 109 are formed of
the same conductive member. The transmission line transmits
frequency signals of several kHz or more. On the other hand, the
change in electric charge generated by the piezoelectric film 150
is about several Hz to dozens of Hz. Therefore, in the case where
the signal line conductor 105, the first detection electrode 107,
and the second detection electrode 109 are made of a common
conductive member, it is possible to distinguish between a signal
(a piezoelectric signal) from the first detection electrode 107 and
a high frequency signal from the signal line conductor 105.
Accordingly, it is not necessary to separately provide wiring
lines, and it is possible to achieve space saving. Further, it is
possible to reduce the number of poles of the connector. A more
desirable aspect is that, in the first detection electrode 107 and
the signal line conductor 105, signals are synthesized by a
frequency discrimination circuit like a Bias-T or a diplexer, and
the signals are transmitted through the same wiring line. In front
of the amplifier circuit of the piezoelectric signal, a signal (a
piezoelectric signal) from the first detection electrode 107 and a
high frequency signal from the signal line conductor 105 are
branched by the frequency discrimination circuit, and connected to
desired circuits, respectively. Accordingly, it is possible to
suppress deterioration of the characteristics as compared with the
case where separate wiring lines are used.
[0046] Subsequently, FIGS. 7(A) and 7(B) are views illustrating an
example of an arrangement aspect of the deformation detection
sensor in the casing 50. The example of FIG. 7(A) has the
transmission line and the piezoelectric element disposed on the
side surface of the casing 50. The volume operation unit 501 and
the volume operation unit 502 are disposed on the side surface of
the casing 50. The user presses the position of the volume
operation unit 501 or the volume operation unit 502 disposed on the
side surface of the casing 50 to perform the volume change
operation.
[0047] The example of FIG. 7(B) has the transmission line disposed
on the bottom surface of the casing 50, and the piezoelectric
element is disposed on the side surface of the casing 50. The
volume operation unit 501 and the volume operation unit 502 are
displayed on the side surface of the casing 50. The user presses
the position of the volume operation unit 501 or the volume
operation unit 501 disposed on the side surface of the casing 50 to
perform the volume change operation.
[0048] In this case, as illustrated in FIG. 8, in the deformation
detection sensor 10 a bent portion (a curved portion) is present
between the side of the transmission line and the side of the
piezoelectric element. Thus, it is possible to reduce transmission
of the distortion on the side of the piezoelectric element to the
side of the transmission line.
[0049] It is to be noted, each of the above embodiments is the
aspect in which the piezoelectric element and the transmission line
are not overlapped in a planar view. However, as illustrated in
FIG. 9, the piezoelectric element and the transmission line may be
laminated and overlap each other.
[0050] In the example of FIG. 9, the piezoelectric film 150, the
first detection electrode 107 and the second detection electrode
109 constituting the piezoelectric element overlap with the signal
line conductor 105 constituting the transmission line in a plan
view. The second ground conductor 104 is disposed on the lower
surface side of the piezoelectric element. The second ground
conductor 104 functions as a shield conductor of the transmission
line and also functions as a shield conductor of the piezoelectric
element.
[0051] In the structure of FIG. 9, there is a common shield
conductor, which is harder than the resin base material, between
the piezoelectric element and the transmission line. Therefore,
even when the piezoelectric element side is pressed, the resin base
material on the side of the transmission line does not deform
greatly and the impedance of the transmission line does not change
greatly. In this case, the area occupied by the deformation
detection sensor 10 is reduced, which enables the sensor to be
placed in a narrow space.
[0052] It is to be noted, in this embodiment, as an example, the
deformation detection sensor detects the pressing operation at the
position corresponding to the volume change operator to receive the
volume change operation. However, another configuration may be
adopted where the deformation detection sensor receives the
pressing operation at positions corresponding to various operators
such as a power button, a home button, and mute button. Further, an
electronic component such as an amplifier circuit, a matching
circuit or a control circuit may be mounted on the deformation
detection sensor. Mounting the electronic component on the
deformation detection sensor allows for, for example, a reduction
in influence of surrounding noises on a signal from a pressure
sensor.
DESCRIPTION OF REFERENCE SYMBOLS
[0053] 1: electronic device [0054] 10: deformation detection sensor
[0055] 50: casing [0056] 81: battery module [0057] 101: first
ground conductor [0058] 102, 103: resin base material [0059] 104:
second ground conductor [0060] 105: signal line conductor [0061]
107: first detection electrode [0062] 109: second detection
electrode [0063] 150: piezoelectric film [0064] 170: conductive
thin film member [0065] 171: printed circuit board [0066] 181:
printed circuit board [0067] 501, 502: volume operation unit
* * * * *